A "rather large amount" of Timmothy Pitzen's blood was found in the back seat of his mother's vehicle after her suicide, Aurora police said Thursday as their search for the missing 6-year-old neared its third month.

Timmothy last was seen May 13, one day before Amy Fry-Pitzen was found dead in a Rockford motel. Police previously said she left behind a note saying the boy was "with people who love him" and would never be found.

On Thursday, police marked the approaching three-month anniversary of the boy's disappearance by revealing several new details of their investigation, including the discovery of blood in the mother's 2004 Ford Expedition using chemical tests.

"Upon testing it, they discovered the blood belonged to Timmothy; however, it is not known how long the blood had been in the vehicle," Aurora police spokesman Dan Ferrelli said in a statement. "Timmothy's family said it is possible that it resulted from a bloody nose the boy suffered in the past 12 to 18 months."

"It was a rather large amount of blood," Ferrelli said.

Ferrelli said detectives also tested a box cutter Fry-Pitzen used to kill herself, but found only her blood on it. Still missing were the 43-year-old's cellphone, I-PASS device, and clothes she was seen wearing on several surveillance videos.

Tollway records indicate Fry-Pitzen drove to the Dixon area southwest of Rockford on Feb. 18, police said, despite having no known ties to that region. Police said her vehicle went through Aurora's Orchard Road Plaza around 4 p.m. and left Dixon shortly before 9 p.m. before returning to Aurora.

Police said Fry-Pitzen made a second trip to the Dixon area on March 20, with I-PASS records showing her leaving Aurora shortly after 9 a.m. and returning more than seven hours later, at 4:30 p.m.

Ferrelli said her vehicle was "visibly dirty and had growth that was similar to tall grass or weeds underneath" when investigators examined it. He said a forensic team was still processing the vehicle Thursday.

"It is hoped that the materials found on the vehicle are indigenous to certain areas," he said, "which could be targeted for further investigation and possible searches."

The last area that detectives can tell Timmothy and his mother were together was in the I-88 and I-39 corridors near Dixon, Rock Falls and Sterling on May 13. Authorities said cellphone triangulation shows Fry-Pitzen made a call about 1:30 p.m. that day from an area about five miles northwest of Sterling, near Route 40.

Fry-Pitzen's missing clothes were described as a pair of brown Capri pants, a pair of sandal-type shoes with high soles, and a white or light pink top. Police said they also are still looking for Timmothy's Spider-Man backpack, toys and other items missing from his mother's vehicle.

Over the past three months, authorities have carried out several searches for the boy but without results.

Last week, Ferrelli said, police received a reported sighting of Timmothy at a restaurant in Wisconsin Dells but it turned out to be false. Otherwise, he said, "tips really have been slow in coming in," despite the offer of a $5,000 cash reward.

"The fact of the matter is that we don't have any leads that will either disqualify or advance any of the theories in the case," he said. "It's very frustrating for everyone involved. Police officers tend to take cases involving children very personally, and to know that Timmothy has not yet been found is very upsetting."

In addition to investigation details, police released two home videos of Timmothy from November 2010, surveillance footage of his mother taking him out of his Aurora elementary school on May 11, and a more recent photo of Timmothy.

Police said Timmothy is white, stands about 4 feet, 2 inches, weighs 70 pounds, and has brown hair and brown eyes. They asked anyone with information on the case to call (630) 256-5500 or 911. To remain anonymous, call (630) 892-1000.